Circadian analysis of miocardial infarction incidence in an Argentine and Uruguayan population

CARLOS E. D'NEGRI; LEONARDO NICOLA SIRI; DANIEL E. VIGO; LUIS A. GIROTTI; DANIEL P. CARDINALI

Los Cocos

Congreso; VIII Latin American Symposium of Chronobiology; 2005

To report the 24-h variation of myocardial infarction (MI) occurrence in patients recruited from CCU located in Argentina and Uruguay a cohort of 1063 patients admitted to the CCU within 24 h of the onset of symptoms of an acute MI was examined. MI incidence along the day was computed in 1 h-intervals. A minimal MI incidence between 03:00 and 07:00 h and the occurrence of a first maximum between 08:00 and 12:00 h and a second maximum between 15:00 and 22:00 h were verified. The best fit curve was a 24 h cosinor (acrophase ~ 19:00 h, accounting for 63 % of variance) together with a symmetrical gaussian bell (maximum at ~10:00 h, accounting for 37 % of variance). A similar picture was observed for MI frequencies among different excluding subgroups (older or younger than 70 years; with or without previous symptoms; diabetics or non diabetics; Q wave- or non-Q wave-type MI; anterior or inferior MI location). Proportion between cosinor and gaussian probabilities was maintained among most subgroups except for older patients who had more MI at the afternoon and patients with previous symptoms who were equally distributed among the morning and afternoon maxima. The results support the existence of two maxima (at morning and afternoon hours) in MI incidence in the Argentine and Uruguayan population.